JavaScript: Create a function that invokes fn with a given context

JavaScript fundamental (ES6 Syntax): Exercise-59 with Solution

Invoke Function in Given Context

Write a JavaScript program to create a function that invokes fn in a given context. Optionally add any additional variables to the arguments beginning.

• Return a function that uses Function.prototype.apply() to apply the given context to fn.
• Use the spread operator (...) to prepend any additional supplied parameters to the arguments.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2
// Define a function 'bind' to bind a context and arguments to a function.
const bind = (fn, context, ...args) =>
  // Return a new function that applies the original function with the provided context and arguments.
  function() {
    return fn.apply(context, args.concat(...arguments));
  };

// Define a function 'greet' to concatenate a greeting with a user and punctuation.
function greet(greeting, punctuation) {
  return greeting + ' ' + this.user + punctuation;
}

// Define an object 'freddy' with a 'user' property.
const freddy = { user: 'Morning' };

// Bind the 'greet' function to the 'freddy' object.
const freddyBound = bind(greet, freddy);

// Call the bound function with additional arguments.
console.log(freddyBound('Good', '!')); // Output: "Good Morning!"

Output:

Good Morning!

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-59-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that creates a function which invokes another function with a specified this context.
• Write a JavaScript function that uses Function.prototype.call to execute a function in a given context.
• Write a JavaScript program that binds a function to an object and then immediately invokes it with additional arguments.

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